Are women more likely to put on pounds after menopause? What happens in the body that makes it seem easier to gain and harder to lose weight around the time of menopause? Is there anything a woman can do to combat changes in body composition?
Menopause is a transition period in many aspects (see Figure 1 for definitions dealing with menopause). It is associated by many women with undesirable changes in body composition, as well as a redistribution of fat from the periphery to the center. In general, body composition shifts include greater fat mass and less lean tissue for postmenopausal women (13). In addition to these shifts in composition is an increase in abdominal fat (11). Accumulation of abdominal fat is a concern with regard to a number of diseases, including cardiovascular disease and type 2 diabetes.
Midlife weight gain is unfortunately a reality for many women. Women often attribute these changes entirely to menopause, although aging itself likely plays the significant role. How menopause, with its declining estrogen levels, or chronological aging is involved becomes somewhat irrelevant as, from a very practical perspective, neither aging nor menopause is an aspect women have the opportunity to change. Although a topic of interest for some researchers, from a public health standpoint, a more relevant question may be to find factor(s) that women can modify (13). This article will examine how physical activity may provide a key for women to maintain body weight and optimize body composition.
Body weight is related to the difference between energy intake and energy expenditure. If more calories are consumed than expended, weight gain will occur. To decrease body weight, fewer calories should be consumed and/or more calories must be expended. In general, to maintain body weight, the consumption and expenditure must be basically equal over time. For more information on the dietary side of this equation (i.e., intake), please see these resources available from the U.S. Centers for Disease Control and Prevention (http://www.cdc.gov/nutrition/index.html) and the Weight-Control Information Network (http://win.niddk.nih.gov/publications/better_health.htm).
The energy used throughout any given day (i.e., expenditure) can be divided into three main categories (see Table 1 for the relative contribution of each). The first two categories include those which provide energy for basic body functions at rest, referred to as basal metabolic rate (BMR), and the energy expended to process food, referred to as the thermic effect of food. Physical activity is the third category and can be a major or minor contributor depending on the person.
The energy requirements of cells, tissues, and organs in the body comprise the BMR. BMR declines approximately 2% to 3% per decade. This lower energy cost at rest can result in increases in body weight because overall daily caloric expenditure is lower. It is not clear if menopause specifically influences this rate of decline (11). One factor influencing the BMR is the amount of fat-free mass (11). Muscle tissue has a somewhat higher energy requirement than fat tissue. Unfortunately, losses in muscle mass are the norm with aging, as body composition shifts to a higher percentage of fat (11). Although, conceptually, resistance training provides benefits due to increased fat oxidation, increased ability to do activities of daily living, and potentially through increases in muscle mass (2), given the limited research related to muscle mass changes for older women, resistance training alone is not a likely mechanism for weight maintenance or weight loss. However, resistance training should be included as part of a comprehensive program for the overall health benefits (e.g., bone health).
Similarly, it is not known if menopause influences the thermic effect of a meal. The energy to process, absorb, and digest nutrients in food requires energy, approximately 10% of the daily energy expenditure (11). The thermic effect of a meal is therefore not a major contributor to energy requirements in the body. In general, meals with more carbohydrate and protein elevate energy expenditure following the meal to a greater extent than a high fat meal (11).
Although the BMR and the thermic effect of food can differ over time, the energy expenditure due to physical activity can vary widely and potentially be a major factor related to the total daily energy expenditure. Sedentary individuals may expend as little as 15% of calories in physical activity (e.g., work-related and other activities of daily living) (11). In contrast, highly active individuals may expend up to 50% to 60% of calories taken in on a daily basis to fuel their activities (11). Whether menopause uniquely influences the calories used in physical activity is an area without conclusive evidence at this point (11). It seems more likely that voluntary decreases in physical activity level, shifting to a more sedentary lifestyle, is the major factor rather than hormonal changes observed at menopause. Realizing the potential benefits of a regular program of planned physical activity is a step toward avoiding weight gain around the time of menopause.
Decreasing activity levels and increasing sedentary lifestyles allow for increases in body weight via additional body fat accumulation. Postmenopausal women in one study were found to expend 130 kcal per day less than premenopausal women (11). If energy intake is not adjusted, this will result in a positive energy balance (i.e., more calories being consumed than expended). Weight gain is the result of positive energy balance. Another recent research study indicated that the average weight gain in middle-age women equates to an energy imbalance of only approximately 10 kcal per day (3). It is encouraging to consider that small sustained changes in modifiable behaviors could prevent further weight gain, including adjustments in dietary intake, increased physical activity, and decreased sitting time (3).
Energy expenditure resulting from moderate-to-intense physical activity is associated with lower body mass index as well as less abdominal obesity in postmenopausal women (9). Although body mass index (see Figure 2 for explanation of body mass index and how to calculate it) does not take into account body composition, it is a simple measure that predicts health risks (1). BMI of 25 kg/m or higher is a concern with regard to weight-related health problems (1). BMI of 25.0 to 29.9 kg/m is considered to be overweight, and a BMI of 30.0 kg/m or higher is considered obese (1). The reference range with regard to classification of disease risk for BMI is 18.5 to 24.9 kg/m (1).
The Women's Healthy Lifestyle Project is a strong example of the benefits of lifestyle changes on avoiding gradual weight gain as often seen around menopause. In this 54-month study, women were tracked from perimenopause to postmenopause; women were randomly assigned into one of two groups. One group incorporated a lifestyle dietary and physical activity program (intervention group), and the other group received no intervention (control group) (12). The women in the intervention group participated in a number of educational sessions, including sessions on recipe modification, social support, restaurant eating, and food labeling to promote dietary adherence. The goal for the first month included a balanced low calorie/reduced fat meal plan including 1,300 kcal per day with 25% of calories from total fat, 7% from saturated, and 100 mg cholesterol; in subsequent months, participants could modify the meal plan according to their taste preferences (12). The physical activity goal included 1,000 to 1,500 kcal per week, and participants were given ongoing consultations to help develop and adhere to their activity program (12). The results are encouraging. The lifestyle intervention group was better able to prevent weight gain as evidenced by a small weight loss (0.1 kg or 0.2 lbs) compared with the control group who gained weight (2.4 kg or 5.3 lbs) (12). In addition, waist circumference, a simple measure used to reflect abdominal obesity, decreased more in the intervention group than the control group (difference between the two groups was 2.4 cm or almost 1 inch) (12). Adherence to the physical activity program was associated with better long-term weight maintenance (12). This study shows the benefits of behavioral intervention to avoid weight gain and increases in waist circumference. Although not every woman can receive the direct counseling available through this study, there are many resources available at no cost that provide beneficial information on starting and maintaining an exercise program (Table 2).
IMPLICATIONS FOR HEALTH
Prevention of weight gain is a worthy goal considering the relationship of obesity to chronic conditions including coronary heart disease, hypertension, stroke, type 2 diabetes, and some cancers. In particular, heart disease is a concern for women. Although women often identify breast cancer as the leading cause of death (39% in one Gallop poll), heart disease is actually the number one killer of women in the United States, and incidence increases with advancing age (14). Although women are affected by heart disease at a slightly higher rate than men, one study revealed that 43% of women were not aware of heart disease as a risk factor for death (7). Risk factors for heart disease are included in Figure 3; in particular, note that obesity and inactivity have been found to independently contribute to the risk of heart disease in women (8). These two factors, obesity and a sedentary lifestyle, have been described as "parallel, interrelated epidemics in the United States that contribute to increased risk of [coronary heart disease]" (10). Focusing on both activity and body weight is important for women. In the Women's Health Study, heart disease risk associated with high body mass index was reduced by increased physical activity, but the risk was not completely eliminated. The value of both physical activity and maintenance/attainment of normal body weight is clear (15).
EXERCISE AND LIFESTYLE RECOMMENDATIONS
Findings from one very large study, the Study of Women's Health Across the Nation (SWAN) suggest that regular physical activity may help to mitigate the tendency for weight gain and adverse changes in body composition and fat distribution that accompany aging and the menopausal transition (13). Women should therefore be encouraged to begin, or to continue, with their exercise programs. A balanced exercise program should be the focus for every woman.
Unfortunately, when looking at Healthy People 2010 data, approximately 40% of women report no leisure time activity, just under 30% engage in regular exercise, and only 17% engage in muscular strength training (6). Thus, women are not realizing the full potential of physical activity, as ideally 100% of women would engage in regular aerobic and resistance exercise and no one would report a lack of leisure time activity. In addition to the positive effects on body weight and composition, documented benefits related to cardiovascular and bone health, as well as potentially with menopausal symptoms, should provide encouragement to women to include physical activity in their daily routines (4).
The ACSM Position Stand on Appropriate Physical Activity Intervention Strategies for Weight Loss and Prevention of Weight Regain for Adults published in 2009 supports the use of physical activity in managing a healthy body weight (2). Three aspects are considered in the Position Stand: preventing weight gain (maintaining weight), promoting weight loss, and preventing weight regain after weight loss.
The amount of physical activity needed to prevent weight gain in adults seems to be between 150 and 250 minutes per week of moderate-intensity physical activity (2). Moderate physical activity is defined as approximately 3 to 6 METS; an example of a common activity in this range would be brisk walking. Thus, if a person planned a walking program 5 days per week, the goal time would be 30 to 50 minutes per day.
To actually promote weight loss, the ACSM Position Stand suggests that higher amounts of physical activity may be necessary (>250 minutes per week) (2). This higher amount of physical activity also may be needed to maintain weight loss (i.e., not to regain the weight), although more research is needed to provide stronger evidence for this recommendation (2).
Most research has focused on aerobic activity as it relates to weight maintenance/loss, given the higher energy expenditure of endurance exercise compared with resistance training. The ACSM Position Stand notes that resistance training when combined with an aerobic exercise program has the potential to increase loss of fat mass (2). Although resistance training alone has not been found to promote significant weight loss (2), it provides many other health benefits (e.g., improving bone health and lessening the physiological stresses of activities of daily living) (1). Considering the loss of muscle that occurs with aging, women should consider the addition of resistance training to their physical activity program. Typical recommendations for resistance training include 2 to 3 days per week with at least 48 hours between training sessions for a given muscle group (1). For healthy adults, 2 to 4 sets of 8 to 12 repetitions with rest intervals of 2 to 3 minutes will improve fitness; for older (≥65 years of age) or younger adults (50 to 65 years of age) who are very deconditioned, one or more sets of 10 to 15 repetitions are recommended (1).
Although not specifically linked with body weight or composition, flexibility also is a recommended component for a woman's exercise plan (5). Stretching exercises are recommended for all adults (1). After a warm-up, all major muscle groups should be targeted. Static stretches (i.e., where the muscle is lengthened and then held in that position for 15 to 60 seconds) is typically recommended as part of a general fitness program (5).
SHORT ANSWERS TO OUR ORIGINAL QUESTIONS
To return to the three questions posed at the beginning of this article, the benefits of exercise for women are clear. Considering what factors can be modified - there is no halting the aging process or avoiding menopause - physical activity is one aspect women can control.
- Are women more likely to put on pounds after menopause?
- ○ Not necessarily - women need to stay in energy balance by matching caloric intake with energy expenditure. A balanced exercise program is vital throughout the life span and especially at the menopausal transition.
- What happens in the body that makes it seem easier to gain and harder to lose weight around the time of menopause?
- ○ Many factors may be involved including modest declines in metabolic rate observed with aging and decreases in habitual physical activity. Without making adjustments in caloric intake over time, weight gain will result.
- Is there anything a woman can do to combat changes in body composition?
- ○ Yes - a balanced exercise program is a lifestyle modification that seems to provide benefits related to body composition.
Finally, to consider the question within the title, is weight gain at menopause inevitable? The answer clearly is no.
CONDENSED VERSION AND BOTTOM LINE
Menopause is a time often associated with undesirable increases in body weight and increases in body fat while lean mass decreases. Whether these changes are a result of menopause specifically or aging in general may be debated by some. Regardless, it seems that lifestyle modifications, including a focus on dietary factors and physical activity, can help. Physical activity, including both aerobic as well as resistance training, is recommended as part of a comprehensive exercise program for women.
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ACSM's Action Plan for Menopause by Barbara Bushman, Ph.D., FACSM and Janice Clark Young, Ed.D., CHES; Human Kinetics; 2005.
Fitness After 50
by Walter Ettinger, M.D., Brenda Wright, Ph.D., and Steven Blair, P.E.D.; Human Kinetics; 2006.
Strength Training Past 50
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Keywords:© 2010 American College of Sports Medicine.
Physical Activity; Body Composition; Women; Aging; Obesity